Continuous inductive train control



Sept. 2 8 1926.

C. S. BUSHNELL CONTINUOUS INDUOTIVE TRAIN CONTROL 1924 2 sheets-'sheet 1Filed Sept. 20,

Sept. 28 1926. A C. S. BUSHNELL CONTINUOUS INDUCTVE TRAIN CONTROL FiledSept. 2O 4 1924 Sheets-Sheet 2 F\G.2. Y @PB 57 e8 S9 -,L C B 100 3?- 3108 55 r mi? Patented Sept. 28, 1926.

UNITED STATES PATENT orricE.

CHARLES S. BUSHNELL, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAIL-WAY SIGNAL COMPANY, 0F ROCHESTER, NEW YORK.

CONTINUOUS INDUCTIVE TRAIN CONTROL.

Application filed September 20, 1924. Serial N'o. 738,878.

This invention relates to automatic train control systems for railways,and more par-v ticularly to the provision of suitable automatic meanswhich requires the engineer to take appropriate action, convenientlytermed acknowledgment, at or near each stop signal, otherwise anautomatic application of'the brakes occurs and the train is brought to astop',.or other suitable penalty is inflicted.

More specifically, in accordance with the Vpresent invention, it isproposed to require the engineer to perform an acknowledging act atsuccessive points or intervals of distance in the travel of the trainwhile running under a stop signal through a danger or occupied block.lect an interval-of distance for such recurrent acknowledgment as willcause the acknowledgment to take place at the first` stop signalencountered by'a Atrain and at, or`

closely adjacent to the succeeding stop sig'- nals. In the form of theinvention illustrated, acknowledgment of each caution signal isrequired, in addition to the ac-V knowledgment of successive stopsignals; but obviously the acknowledgment of the stop signals may beused alone, ify desired.

IVith the idea of facilitating traffic, and for other reasons, it isproposed in this invention to eliminate the stopping of the train orother penalty for failure to acknowledge if traliic conditions clear` upin the meantime.

In order to protect the acknowledgingV device from abuse, according tothis invention, the engineer must restore this device to its normal orinactive condition in order to consummate the acknowledging act, withthe result that he cannot defeat the purposes of the device bypermanently holding or fastening it in the active acknowledgingposition.

Other objects, Vpurposes and characteristic features of this inventionwill appear as the description thereof progresses.

In describing the invention in detail reference will be made to theaccompanying drawings in which F ig. l illustrates an especially simplerailway signaling system, upon which the trackway apparatus for a simpleform 'of automatic train control system embodying the present inventionhas been superimposed; and

It is proposed to se-` 'assumed to be equipped the same,

Fig. Q'illustrates conventionally and in a diagrammatic and perspectivemanner one form of car-carried apparatus embodying the presentinvention.

Although the present invention is applicable to various types of traincontrol systems, such as intermittent systems of various kinds andcontinuous inductive systems of the three-position type, it has beenshown applied to asimple form of two-position continuous inductive traincontrol system so as to simplify the illustration and descriptionthereof. Y

Referring to Fig. l, the reference characters l designate the usualtrack rails which vare vdivided by insulating joints 2 into blocks inthe usual way, the block I and the adjacent ends of the blocks H and Jonly being shown. Since the variousblocks are like parts of each blockare designated by like reference characters having distinctiveexponents. Using the reference numbers for the "block I, each block hasconnected across its rails at theexit endthereof the usual track battery3 connected in series with the usual limiting resistance 4i; and theentrance end of each block has bridged across the rails thereof theusual track relay 5, which is in this case a direct current relay.Although the present train control system may be used either with orwithout wayside signals of any suitable type, signals Z of the semaphoretype have been illustrated for convenience, without showing their wellknown operating mechanism and control circuits.

In addition to the usual signaling apparatus thus far described.alternating current isgsuperimposed upon the direct current in the trackcircuit by the transformer 6, having its secondary winding connected inselries with the battery 3, and having its primary winding connected tothe transmission line 7 through a front contact S1 ofthe track relay 51of the block J next in advance.

On the railway vehicle or locomotive, which has been conventionallyillustrated by wheels and axles l0 and 1l, is a main control relay MR,which' is adapted to respond to the presence and absence, respectively,of alternating' current fiowing in the track rails ahead of the vehicle.In the particular arrangement shown, this main relay MR is connected tothe output side of an amplifying device A, which includes suitable am- YHowe, Ser.

Ul l

I of Athe amplifier Y trated. lf the train is in a :speed responsiveplifying tubes or audions, sources of energy, timing devices and thelike. The input side A isl connected 'to the coils 12 and 13 onlaminated car elements 14 and 15 which are disposed directly over therails ahead of the train. 'These coils 12 and 13 are connected inseries, so that voltages induced therein due Ato current liowingin onedirection in onerail and in the other direction in the other rail arecumulative and these coilsare preferably timed to resonance for theparticular frequency user, by bridging aci'oss the leads thereof thecondenser -16 of the'proper capacity. Although the 'coils 12 and 13 havebeen shown surrounding cores of laminated magnetic material, thesecoresrnay be omitted inpractice, if

desired V,de ending somewhat on the t ae of v i 3 D amplifying deviceandthe frequency of the alternating current used.

Referring to Fig.l 1, it will be noted that the main relay MR assumesits energized position when the train is moving in a clear block, inwhichj position it has been illluscaution block, the main relay MRassumes de-energized position, because no alternating current lispresent in the track rails directly ahead of the train by reason of thefact that the track relay of the block neXt in advance, under theassumed caution condition, in the de-energized position, and thetransformer 6 is disconnected from the transmission line 7. On the otherhand, when the train in question follows another train in the sameblock, it is deprived of, alternating` current even if such current isapplied to the exit end of the block, because such alternating currentis shunted away from the following train in question by another saidtrain ahead in the saine block. The response of this main relay hilt tochangGS in traffic conditions ahead should be borne in mind inconnection with the description 'of the car apparatus in Fig.2.Referring to Fig, 2 of the drawings, carcarried apparatus of the wellknown cam and governor type has been illustrated; and since the variouselements of the speed control apparatus are well understood by thoseskilled vin theatrt and are described in considerable detail in theapplication of il?. l. No. 33,132 filed July 6, 1915, this apparatuswill only be briefly described. 1n the arrangement shown, a centrifugaldevice or centrifuge C is supported on a shaft 2() driven from the`wheels ofthe vehiclein any suitable manne-r.

The grooved collar 21 of the centrifuge C moves downwardly as the speedof the vehicleincreases, so that'the speed shaft 22,

1 which `is operatively connected to this collar V clockwise directionas lconnected. a floating paratus illustrated, the speed of the train isabove the minimum speed enforced by this speed controhapparatus, whichVminiiiiuin speed is assumed to be 15 miles per hour. Fixed on the shaft20, drive-n from the wheels of the vehicle, is a worin 24, which is incontinuous meshed relation with a worin wheel 25 pinned to a shaft 26. Apinion 27, pinned to the shaft 26 is in `continuous ine-shed7 relationwith gears 23aiid 29 which are pivotally supported on journals 30 Vand31, respectively. 'y A bifurcated or forked arin 32 has its bifurcatedend straddling the gear 28' and is pivotally secured on the journal 30,sorthat this arni may swing 'concentrically with the gear 28 about thejournall 30. ln the bifurcation of this arm is pivotally journaled apinion 33 in a manner so that it continuously meshes 'with thefgear ASv.This arm 32 is urged upwardly by a tension spring 34 but is normallyheldin its lower position, against the tension of this spring, by thearmature. 35 attracted by the speed control cam `starter magnetSimilarly, a pinion 36 is carried iii-the bifurcated a'rin 37 held inits lower position by an acknowledging cani starter niagnet CSA, the arm37 being urged upwardlydby a spring 33. Y Y

Directly above the pinion 33 and in alignincnttherewith, is'd'isposed amutilated gear 40, which is pinned Atoadistance 'shaft 41, so as to turnthis shaft in accordance with the progress of the train 4while themutilated gear 40 is in rnesh with the pinion 33. To the distanceshaft'41 are firmly secured for rotation therewith a? permissiie speedcam 42 and four 'distance cams 4,3, 44, 45 and 46. rlhese distance cams,through suitablerollers cooperating therewith, areradap't'ed to closecontacts 47, 7 3, 48 and 51 respectively, during various angularpositions of this distance cani shaft 41.

To the speed shaft 22 is secured a speed arm 17, to the free end ofwhich is pivotally lever 1S, having a roller 19 at the free end thereofwhich rides against the cani surface of the cam 42. Ey observing themanner in which this floating lever 13 is supported, it is obvious thatall that is necessary in order to operate suitable contacts inaccordance with the speed 'of the train as con pared with the permissivespeed set up rby cani 42, is 'to operate such contacts in accordancewith the position'of an intermediate point on this floating lever 13. lnthe particular arrangement shown, this has been accomplished byproviding a sector 52, pivotally supported on a journal and having aneccentrically located pin 54 thereon, which is connected to anintermediate point on the floating lever '.13 by a link 83. This sector52 'is biased in a lcounter-clockwise direction by the spring 39 and isshaped so as to cause contacts 33 to open when the actual speed of thetrain is higher than the permissive speed setup by the permissivel.adaptec'hthrough the medium of rollers engaging the surface of thesecams to opera-te contacts 6l, 62, 63 and 64, respectively, at variousangular positions of the acknowledging shaft 55.

Since` the present invention does not relate to any particulartype ofapparatus for applying the brakes cf the usual air brake system, nospecific type of device for carrying out this `function has beenillustrated. An electro-pneumatic valve EPV has, however, been shown,which may be used to actuate the usual engineers brake valve in a mannerso that the engineer may notr prevent its operation, or which maybe usedto operate a suitable application valve, which vents the brake pipe andcutsthe main reservoir pressure loft the'engineers brake valve so thathe cannot recharge the brake pipe While this application valve is in itsactive position.

rIhe acknowledging device or contractor is shown as a simple button PB,resilient or Yspring returned, and having normally open and normallyclosed contacts. This push button PB is located at some convenient pointin the cab and in easy reach of the engineer, and is enclosed in arsuitable locked or sealed casing, with only an operating memberprojecting', so that the engineer cannot interfere with the electricalconnections.

Operation.

Afrom the terminal B of a suitable source of energy, which has its otherterminal connected to a common return wire C, which circuit includes afront contact ofthe main con-v trol relay MR. IVith the distance shaft4l in its normal position by reason of the energization of the camstarter magnet CSS,

f the cam starter magnet for the acknowledging shaft 55 is energizedthrough a'circuit as follows Beginning at the terminal Bof a suitablesource of energy, wire 66,v contacts 47 operated by the distance cam 43,Wire 67, contacts 6l operated by the distance cam 57, wire G8, windingof the cam starter mag.- net CSA, wire 69 back to common return wire Cto the other terminal of said source.

The penalty relay PR is .normally en.- ergized by the following circuitbeginning at the terminal B, wire-72, contacts 73 andV 49 of thedistance cam 44, wires74 and 75, conta-cts 5l of the distance cam 46,wires 76 and 77, front contact 78 of the penalty relay PR, wires 79 and80, winding of the penalty relay PR, wire Sl, back to the common returnwire C. There are several other circuits by which the penalty relay PRis normally energized, but these can more advantageously be consideredhereinafter.

Under normal conditions of the apparatus' A when the train is moving atan intermediate speed, as heretofore assumed,the electropneumatic brakecontrol device EPV is energized through the following circuitz-beginning at the terminal B, wire 82, cam and governor contacts 83,wire 84, front contact 85V of the penalty relay PR, wire 8G, winding ofthe .device EPV, wire 87, back to common return wire C. From thiscircuit, it will be noted that the device EPV is. cle-energized ifeither the governor-cam contacts 83 or tne front contact 85 of thepenalty relay PR are opened.

Maximum speed limit-While the train is traveling in a clear block, thebrakes are automatically applied if a predetermined maximum speed isexceeded. Referring to Fig. 2, it will be evident that, after a certainspeed has been reached, the lower end of the floating lever 17 will havebeen moved far enough vto the left, with the cam 42 in the normalinitial position shown, to canse opening of the contacts 83, therebyde-energizing the brake controlling valve EPV. As soon as the speed ofthe train is brought down by such automatic brake application below themaximum normal running speer., the contacts 83 close again, the valveEPV is again energized, and the engineer may release the brakes.Consequently, there isY no particular penalty for exceeding the maximumspeed limit under clear traflic conditions.

Uri-ation Hoda-Let us now consider the operation of the car-carriedapparatus, as the. train moves from the block H which is assumed to beclear toward the right when the block' J next in advance is occupied,that is, when the block I is a caution block. As the train moves intothe vblock I, the main relay MR assumes its cle-energized position, thecam starter magnet CSS is cle-energized, and the pinion 38 comes .intomeshed relation with the mutilated gear 40, turning the distance shaft4i in one direction or the other depending on whether the train ismoving pilot entender first. After a short distanceiof movement lil()ffii) 'of the train, -tal line 4S .-in Fig.

to common return wire C.

as indicated by the horizon- 1 ofthe drawings, the contacts 48 operatedby the distance cam u-close. Thefclosure of these contacts causes theacknowledging signal Ack S to sound, giving the-engineer a warning thathe must now manifest `his vigilance by operating the acknowledging' pushbutton PB in order to ayoidan automatic brake application. The circuitfor sounding` this signal `may be Atraced as Ylkllows1-beginning at theterminal '15, wire 90, `contacts 48 operated by distance cani 45, wires91 .and 92, back contact 93 of the acknowledging relay Ack R, wire 94,acknowlec ging signal. Ack S, wire 95 lv ck to common return wire C.

fldroceeding on the assumption that the engineer is vigilant`andresponds promptly by depressing the push button BB, la pickv.upcircuit for the acknowledging relay Ack R- is completed asfollowsz-beginning at ithe .terminal B, wire-9G, acknowledging pushbutton flp, wires 97 and 98, winding of the acknowledging relayrAck R,wire 99, back With this acknowledging relay Ack R once picked up, astick circuit for this device is completed which may be traced ras'follows z-beginnin at the terminal B, wire 90, contacts 48 of thedistance cam .45,wires 91 and. 92, contact 93 of the acknowledging relayAck R in its 'raised position, wires 100, :101 and 98, winding of theacknowledging rrelay rick R, wire 99, back to common ret-urn wireiC. Atshould be noted that Vthe acknowledging signal is discontinued vas .soonas the acknowledging relay Ack R is energized, be cause theacknowledging signal circuit includes the back vcontact ofarmature 93 of`this relay.

i/rftera further short distance of travel, as indicated by a solidlportion of horizontal lines 49,:and 50 in VFig'. `1 compared with thehorizontal line 48, the .contacts 49 yopen and the contacts 50' close.These contacts are operated by -the distance cani 44 and used for thepurpose of makingl the requirement rof acknowledgment by theacknowledging shaft hereinafter to be explained effective or ineffectivedepending on the position of' the distance shaft 41. lliththe contacts49 open, the main stick circuit for thevpen- .alty relay PR heretoforetraced is no longer intact, but another stick circuit which mayvbetracedvas follows maintainsithe penalty relay PR energizedzbeginningat the. terminal B,.wire 104, contacts 63, .operated by theacknowledging -cam 59, wires and .7 5, contacts 51 operated bythedist-ance cam 46, `wires 7.and 77, front contact 78 of the penaltyrelayPR, wires 79and 80, winding of the ypenalty relay PR, wire 81 `backto common returnv wire fetter a further short distance of travel,

which 'may bey observed. by looking at the fact that .the engineer :soas to energize't-he y Ack R, as has been assumed, he .has comknowledgingrelay fick R,

.neo-1,427

vhorizontal-linesin Eig. 1, the contacts 51 open for a short distance oftravel, as indicated by the dotted portion Aof the line 51 (see Fig. 1).Opening of contacts 51 inter rupts the stick circuit Jfor the penaltyrelay PB heretofore traced, but by reason of the l was vigilant andoperated the acknowledging push button FB, acknowledging relay pletedanother stick circuit for the penalty relay PR which may be traced asfollows tbeginning at the. terminal 13, wire 96,7push button contact PB,wire 198, front contact v109 of the acknowledging relay Ack flhwires 110Vand 77, front Contact 78 of the penalty relay PR, wires Z9 and 80,ywinding ofthe -penalty relay 13R, wire S1 back to the common returnwire C. 1t should be notedthat this penalty relay stick contact of thepush button PB closed in its normal position, so that the engineer isnotI only required to operate the push button, but is required to returnit to 'normal sofas to consummate the acknowledging act. 'Had theacknowledging relay notbeen stuck up or the acknowledging push buttonbeen retnrnedfto normal, the device EPV would rhave beencle-energized,because of dropping of the Contact 85 of the penalty relayPR. The contacts o1 are opened for a'shortdistance of travel only (seethe Vhorizontal line 51), and a short distance of travel after herecontacts 51 are again closed, the contacts 48 again open. The opening ofcontacts 48 breaks the stick circuit :for ltheacthereby causing itsnormal dethis relay [to again assume venergized position.

As thetrain now proceedsthrough the caution b-lock I, the block J neitin vadvance remaining occupied, the permissive speed set up by thepermissive Vspeed cam 4Q gradually decreases, thereby requiring theengineer to reducehis speed substantially as indicated bythecurye 106(Fig. 1') to avoid an automatic brake,application'by opening of thecam-governor vcontacts 83. vWhen the train has progressed a distance inthe block .to the Vpoint indicated by the vertical line 107, thedistance contacts 47 open, thereby breaking'the circuit for theacknowledging cam starter magnet CSA, thus cruising' 'the acknowledgingcam shaft `55 tobe rotated inl accordance with the progress of the trainthrough the medium of .pinion-36.

After a short distance of travel with the cam startermagnet CSAdc-energized,'the contactsl open, thereby assuring that this cam startermagnet GSA is not again re-energized until the shaft 55 assumes itsYnormal position. The gear 56 is not provided with a mutilated portion,as is the gear 40s'o that the gear 56 continues to rotate so long asthe, train mores and the nain startem agnet circuit includes the Y pleterotation of the acknowledging shaft' 55. rlhe following stick circuitmaintains the acknowledging relay energized, if it is otherwisemomentarilyV energized beginning at the terminal B of a battery, wire125, contacts G4, wire 126, front contact 127 of the acknowledgingrelay, wires 128, 101 and 98, winding `of the acknowledging relay Ack R,wire 99 and back to the common return wire C. The purpose for whichthese contacts 64 were provided is more readily explained hereinafter.

The rotation of the acknowledging shaft does not change' the function ofthe permissive speed cam 42, this speed cam continuing to reduce thepermissive speed, as indicated by the curve 106, until the permissivespeed has been reduced to its ultimate miniin'um or low limit, assumedto be 15 miles per hour, as indicated by the horizontal line 111.Shortly after the train has been restricted to this minimum speed andwhen the acknowledging shaft 55 has rotated substantially a halfrevolution, this acknowledging shaft closes contacts l62 (see horizontalline in Fig. 1), thereby closing a circuit for the acknowledging signalJ4ck S as follows :-beginning at the terminal B, wire 72, contacts 73and 50 operatedby the distance cam 44, wire 112, contact 62 operated bythe acknowledging cam 58, wires 113 and 92, back contact 93 of theacknowledging relay Ack R, Wire 94, winding of the acknowledging signalAck S, wire 95 back to common return wire C. The sounding of thisaudible acknowledging signal Ack S advises the engineer that her mustmanifest his alertness; and if he does this by depressing the pushbutton PB, the acknowledging relay will again be picked up and stuck up,and the acknowledging signal silenced in the same manner heretoforedescribed.

Upon a further slight movement of theV train the contacts 63 are opened,as indi-- cated by the line 63 (see Fig. 1), and if the engineer hadfailed to operate the acknowledging device because he was incapacitatedor did not attend to his duties for some other reason, opening of thecontact 63 would have interrupted the auxiliary stick circuit for thepenalty relay PR heretofore traced, and would have effected an automaticbrake application, so as to reduce the speed of the train as indicatedby the curve 114 and bring the train to a stop. Since, as has beenassumed, the engineer has performed the required acknowledging act, thepenalty relay stick circuit is held closed by contact 109 of theacknowledging relay. v

it should be borne in mind that the acknowledging relay is now stuck upthrough two stick circuits, one including front contact of armature 93and the other including front contact of armature 127, and that thisrelay will not assume its Cle-energized position until both of thesestick circuits are broken. Upon a further short distance of movement ofthe train, contacts 62 again open and break the stick circuit includingthe front contact 93. When the acknowledging' shaft has substantiallycompleted one revolution, the contacts 64 again separate and the otherstick circuit of the ac- Ack R assumes its Cle-energized position.

As the train continues to move in restricted territory, that is, solongr as the main relay MR is cle-energized, the acknowledging signal isrepeatedly sounded, and acknowledgment is required for reasons justgiven each time the acknowledging shaft 55 completes a revolution afterthe acknowledgment ust considered.

If the train again moves in clear territoryand the main relay MR is11e-energized, the resultant re-energization of the cam starter magnetCSS causes immediate return of distance shaft 41 to its normal position.This return to the distance cam 44 to normal causes the Contact 73 toagain assume its normal position, as shown in the drawings,v

so that the operation of contacts 62 and 63 does not sound theacknowledging signal Ack S or require an acknowledgment by the engineer,even though 'these contacts are operated by the acknowledging shaft 55,

' possibly because this acknowledging shaft `has not yet reached itsultimate normal position. As soon as the acknowledging shaft 55 againreaches its normal position and closes contacts 61, the energizingcircuit for the acknowledging cam starter magnet CSA is again completed,thus causing the pinion 36 and the gear 56 to be disengaged and leavingthe acknowedging shaft 55 in its normal position.

If the engineer has failed to operate the acknowledging device at apoint in the movement of the train when such operation is required andhas for this "reason dropped the penalty relay PR, the device EPV isimmediately cle-energized and remains cle-energized so long as dangertrailic conditions eX- ist, and if traliic conditions in the meantimeclear up and the main relay MR again assumes its energized position, thepenalty relay PR is automatically picked up 'and maintained up by acircuit which may be knowledging relay is broken and this relay` tracedVas follows-beginning at the terminal B, wire 117, front contact 118 ofthe penalty relay PR, wires 119, 120 and SU, winding of the penaltyrelay PR, wire 81, back to common return wire C.

If the engineer fails to manifest his vigilance; for reasons justmentioned, and the penalty relay PR and the device EPV arecle-energized, and traffic conditions do not clear up until the train isbrought to a stop, this penalty relay PR may be picked up as soonassthetrain is brought to a stop by reason of the speed contacts 121which are closed when, and so long, as thespeed of the train issubstantially zero. The circuit through which the penalty relay PR ispicked up after' theI train has been brought to a stopdepends upon thespeed at which. the train is traveling when this relay PR is de-energized. Assuiningthat the train is traveling at a: highy rate of speedand is entering a cautionr block when the engineer fails to acknowledge`and thusy permits the cle-energization ot the relay, PB, the motion ofthe train in being brought to a: stop is sufficient to close thecontacts 5l before the actualstop is made. speed' contacts 121 areclosed, the relay PR is picked up at once through the following circuitz-fronithe battery terminal B, wire 1041, contacts 63 of the cam 59',wires 105 and 75, contacts 51 of the cam 4G, wire T6, contacts 121,wires 120 and 80 and the winding of the relay PR through wire 81 to thebattery terminal- C. lf it should occur because of' a very high. trainspeed at the time that acknowledgment was required that the contacts 63are open when the train comes to a stop, the pickup circuit just tracedis not completed, but the engineer may in this case re'-energize thepenalty relay by operating the push` button PB and energizing theacknowledging relay rick R. Once energized", the acknowledging relay isstuck up through a circuit including` its front contact 127 and thecontacts 611 of the cam 30, which stick circuit has been traced, andwhen the push button PB is released by the engineer and returned to itsnormal position as shown, a pick-up circuit for the penalty relay iscompleted, which circuit may be traced as follows :-from the batteryterminal B, wire 96, push button PB, wire 10S, front contact 109 of theacknowledging relay irck R, wire 110, Zero speed contacts 121,

wires 120 and 80, Winding of the relay PR and wire 81 to the batteryterminal C. 1n

the engineer may re-energizethe penalty relay PR if he has failed toacknowledge at repeat-ed distance intervals while traveling underunfavorable traffic conditions, the stick circuit for the relay havingbeen broken at the contacts 63 of the cam 59 andthese contacts havingremained open after the train has come to a stop, due

the 5211119 111 tllllll ln this case, after the Zei-o Leones? to theslow speed ofthe train. lf theV train is moving very slowly as it firstencounters unfavorable traiiic conditions, and the main' relay MR isfirst cle-energized, the train may be brought to a stop upon the failureof the 'engineer' to acknowledge, while the contacts 51 of the cam e6are still open. 1n this case, the engineer may re-energize the relay PRto permit a reease of the brakes by depressing tlie push button PB asbefore to' energize the relay Ack It, which relay is now stuck upthrough its front ContactV 93 and the contacts 48 ofthe cam Ll5 througha circuit which has been traced above. The return of the push button PBto its normal position closes a pick-up circuit to the relay PR throughthe contacts 109 and 121 as e2;- plained above. ln actua-l practice, ifthe engineer has permitted the relay PR to become cle-energized. byreason of his failure to acknowledge at the proper time, and the trainis brought to a stop, V'f the relay PR'i's not at once automaticallyenergized to permit a release of the brakes the engineer depresses thepush button PB and thus obtains a release from the penalty stop.-

From the above it is evident that ifv the engineer' fails to make anacknowledgingact andtratlic conditions immediately thereafter clear upthe penalty consists only iii requiring him to retard the train byreason of an automatic brake application until traffic conditions doclear up, and if traflic conditions do not immediately thereafter clearup he is penalized to a greater extent, in that he is required to bringthe train to a stop before liercan again proceed.

lt should be noted that it" the stick circuit for the acknowledgingrelayincluding contacts 64 and 127 had'noty been provided, repeatedacknowledgment would have been required if the engineer made switchingmovements back and forth at about a.v point where acknowledgment isrequired. By the provision of this additional stick circuit theacknowledging relay if once picked up is held up for ak half revolutionof the shaft 55 in either direction from the acknowlec 'ging point andthe distance the train would have to travel to drop this relay byopening contacts 6e is greater than what would occur in ordinaryswitching movements. ln this connection it should further be noted thatthe provision of this contact Llpermits the engineer to nialie theacknowledging act before it is really required, and if he does so, theacknowledging signal will not be sounded at the regular acknowledgingpoint.

lt should be noted that all of the distance cams, that is, those on the`acknowledging shaftas well as those lon the distance 'shaft 1-1 aresymmetrical as far as the 'upper and lower halves are concerned.

rl`his construction is used so that the permissive speed perforinance aswell as the requirement for acknowledgment is the same Whether theengine travels l"pilot or tender first. ln practice additional influencereceiving elements are placed in the rear of the last tender axle whichelements are automatically or manually substituted for the elementsillustrated when the engine and tender unit travels tender first insteadof pilot first as illustrated.

Reviewing the characteristic features of the operation of the embodimentof the invention shown, it will be observed that the enforcement ofacknowledgment for the first stop signal is the result of starting theacknowledging` shaft 55, resulting in the opening of the contacts 63. Ifthe engineer fails to acknowledge, the brakes are applied automaticallyupon the opening of the contacts 63; and in order that the train may atall times be g-overned on the side of safety, the system is organizedlsuch that these conacts 63 open at a point near the exit end of theblock which is braking distance for the minimum speed of the system fromthe physical exit end of the block. As indicated in Fig. 1, the contacts63 open at a point where, if the brakes are applied on account of thefailure of the engineer to acknowledge, the train will be brought to' astop at or before reachinon the. end of the block as shown b f thebraking distance curve 114.

Since the point in the block at which the contact G3 open depends upon apoint in the block where the contacts 47 open to start the shaft 55, andthis point in turn depends on where the car relay MR is cle-energized tostart the shaft 41, it will be evident that in practice the trackwaycircuits for the several blocks on the railroad should be organized, byfollowing out well known eXpedients, such as cnt-sections and the like,so that the car relay mit is cle-energized at a fixed distance from theexitend of each block, providing of course the next block in advance isoccupied. If, as sometimes happens in practice, the proper point forcle-energizingthe car relay MR does not come at the en- Arance to cachparticular block, the point for acknowledgment of the caution signal maybe some distance either in the rear or in the advance of the waysidecaution signal itself. For this reason, it is desirable to provide theacknowledging signal Ack S, preferably as an audible signal, to `guidethe engineer in making his acknowledgments. Also, since the cautionacknowledgment may not be at the wayside signal itself, suchacknowledgment does not serve satisfactorily to enforce vigilance on thepart of the engineer in observing thc wayside signals; Vand aside fromshowing that the engineer is alive and not incapacitated, theacknowledgment for the caution signal required by the system shown anddescribed may be omitted.

rlhe gear ratio driving the shaft is preferably selected so as to causeone rotation of this shaft during a distance of travel correspondingapproximately to the normal block length, so that after passing thefirst stop signal, the acknowledgment enforced by the next revolution ofthe shaft 55 will take place near the second stop signal. Suchproportioning, however,lis optional; and if l desired, the shaft 55 maymake one revoluthe ideaof the present invention, it is de-V sired to beunderstood that this has been done for illustrative purposes rather thanfor the purpose of showing the exact mechanism preferably employed inpractice or the range and scope of the present invention, for ins ance.the same general arrangement may be applied to either intermittentor'threeposition continuous inductive type train control systems bymaking suitable additions and changes to adapt the invention to suchsystems without departing from the scope of the. invention or the ideaof means underlying the same.

lVhat is claimed as new and desired to be secured by Letters Patent isy 1. In an automatic train control system, the combination of a speedrestricting device governed in accordance with traflic conditions aheadand initiated if traffic conditions -ahead are dangerous so as togradually reduce the permissive speed at which the vehicle may travelWithout incurring an automatic brake application, normally energizedmeans cle-energized so long as traflic conditions ahead are dangerousfor applying the brakes regardless of the speed at which the train istraveling and effective a predetermined distance after said speedrestricting device has been initiated, and means for preventing saidAlast mentioned means from applying the brakes effective if actuated atrepeated distance intervals.y

2. In an automatic 'train control system, the combination ofa brakesetting appliance, normally energized means maintained deenergized underunfavorable traiiic conditions and acting when ole-energized to requirethe engineer to manifest his vigilance upon the approach of his train toa signal at danger and thereafter at repeated distance intervals byactuating a manually operable device,` and means for actuating saidprising, a, brake exceeds the perniiissive speed, and other.

means i'or rendering said appliance active including means moved in thesame direc` tion as long as active and etiective after the train hastraveled a predetermined distance in dangerous territory unless asuitable manually operable device is operated at rcpeated distanceintervals ot travel.

l. An automatic train control system comprising, a normally energizedstick electro` responsive device which it cle-energized et :tects anautomatic brake application', two independent means 'for maintainingsaid device energized, one of which is effective so long yas the trainis traveling in clear territory and a predetermined distance in danger'territory, and the other oi which includes a device rotated in the samedirection so long as traliic conditions are dangerous, which device iseiective it a suitable manually operable device is operated repeated distance intervals.

5. In an automatic train control system, vehicle-carriedapparatus,comprising a permissive speed means Which applies the brakesof the train it the speed` is excessive, means for initiating` saidpermissive speed means under dangerous traiflic conditions ahead forrendering it active after a given interval of vehicle travel from thepoint initiated to impose a minimum speed restriction, distancegoverned. means rotated in the same direction so are dangerous for succab signal and a device lor long as trai'iic conditions speed after agivenL distance oi?y vehicle travel from the point at which said minimumspeed restriction was imposed, and means including a manually operablemember tor preventing the automatic brake application'regardless ofspeed provided said manually operable member is operated atpredetermined successive intervals o vehicle travel from the point atwhich said minimum speed restriction was initiated.

6. An automatic train control prising, automatic means for effecting abrake application it the speed ot the train is excessive for particularconditions of tratiic ahead, means for eiiecting` an automaticapplication ot the brakes regardless of the speed of the train, manuallyoperable means operable by the engineer for preventing an automaticbrake application by said last mentioned means it operated just prior tothe initiation of such application, means system ceinessively actuatingay imposing` anV automatic brake. application regardless ot forinflicting a` penalty ifran, automatic brake application isl effectedbecause the engineer has 'tailed to operate said manually operablemeans, and means Jfor preventing the inflicti'on or" said' penaltyeiiective iii traffic conditions aheadrlear up before the train has beenbrought to. a stop.

7. Car-carried apparatus for automatic train control systems comprising,a brake set,A ting appliance, means ioractuating said appliance toeffect a brake application if the speed ot the train is excessive,another means for actuating` said appliance regardless of the speed ofthe train, means for making an acknowledging act including a manually operablo acknowledging device which it momentarily operated before saidanother means actuates said appliance is adapted to prevent actuationor' said appliance, and means for protecting said manually operabledevice against misuse requiring said device to be returned to its normalposition in order to complete the acknowledging act,

S. Car-carried apparatus for automatic train control systems comprising,a brake setting appliance, means for actuating said appliance to eii'ecta brake application it the speed ot the train is excessive, anothermeans for actuatingy said appliance regardless ot the speed of thetrain, a stick relay which if energized prevents said another means fromactuating said brake setting appliance, an acknowledging push button, apick-up circuit or said relay including contacts closed when said pushbutton is depressed, and a 100 stick circuit for said relay includingcontacts closed when said push button is in its normal position.

9. Car-carried apparatus for automatic train control systems comprising,a brake 105 setting appliance, means for, actuating said appliance toeiiect a brake application it the speed of the train is excessive,another means for actuating said appliance regardless oi the speed ofthe train, a stick relay which if 110 energized prevents said anothermeans trom actuating said brake setting appliance, an acknowledging pushbutton, a pick-up circuit or said relay including contacts closed whensaid push button is depress-ed, a stick 115 circuit for said relayincluding contacts. closed when said push button is in its normalposition, and means 'for dropping` said stick relay When said anothermeans is ner longer inv condition to actuate said brake set- 120 tingappliance.

10. In an automatic train control system, vehicle carried apparatuscomprising a permissive speed means Which applies the vehicle brakes il'the speed is excessive, means 125 for initiating said permissive speedmeans When dangerous trailic conditions are encountered for rendering itactive after a given distance of vehicle travel from the point initiatedto impose a minimum speed 130 restriction, a normally energizedelectro-responsive sticlt device acting When de-ener gized to impose abrake application and bring the vehicle to a stop, distance responsivemeans initiated by said permissive. ,speed means at a pre-determineddistance or' vehicle travel from the point at which said permissivespeed means is initiated and operated continuously when initiated solong as the vehicle is proceeding under dangerous traliic conditionsahead, apparatus associated With said permissive speed meansfordeenergizing said stick device substantially When said permissive spe-edmeans is initiated, apparatus associated with said distance responsivemeans for de-energizing said stick device at predetermined distanceintervals after said distance responsivel means is initiated, andmanually operable means acting if operated substantially When saidpermissive speed means is initiated and at predetermined distanceintervals after said distance responsive means is initiated to preventthe de-energization of said stick device.

l1. lIn an automatic train control System,

vehicle carried apparatus comprising a normally energizedelectro-responsive sticli device, acting when de-energized to initiatean automatic brake application and bring thev control means at apredetermined distance from the pointI at which said speed control meansis initiated, and acting when initiated to de-energize said stick deviceat predetermined distance intervals so long as the ve Vhicle isproceeding und-er dangerous traiiic conditions, and manually operablemeans acting if operated and returned to its normal positionsubstantially when said speed control means is initiated and at saidpredeterinined distance intervals under dangerous traffic conditions tomaintain said stick'device energized.

In testimony whereof I aix my signature. i

. CHARLES S. BUSHNFLL.

